Updated: 1/25/2020

Soft Tissue Sarcoma

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Introduction
  • Overview 
    • soft tissue sarcomas (STS) are rare malignant tumors comprising a variety of subtypes distinguished by histological findings
      • treatment typically involves mass excision and radiation therapy
  • Epidemiology
    • incidence
      • 7000 new case/year in the United States
    • demographics
      • males > females
      • 85% occur in patients >15 years old
    • location
      • 60% occur in extremities
  • Genetics
    • classic translocations 
      • t(X;18); SYT-SSX fusion
        • synovial sarcoma
      • t(2:13)
        • rhabdomyosarcoma (alveolar)
      • t(12;16)(q13:p11)
        • myxoid liposarcoma
  • Associated conditions
    • neurofibromatosis type-1
      • malignant peripheral nerve sheath tumor (MPNST)
    • Stuart-Treves syndrome
    •  
      • angiosarcoma
  • Prognosis
    • natural history of disease
      • often slow-growing painless mass
      • metastasis is most commonly to the lung 
      • 5% lymph node metastasis (most commonly epithelioid, synovial, angiosarcoma, rhabdomyosarcoma, clear cell)
    • prognostic variables 
      • tumor stage is most important prognostic factor
      • poor prognostic factors include
        • high grade
        • metastatic disease
        • size > 5 cm
        • tumor location below the deep fascia
        • delay in diagnosis 
        • unplanned excision   
          • most common error in STS treatment
          • referral to orthopaedic oncologist for multidisciplinary workup and repeat excision is critical
    • survival with treatment
      • <10% local recurrence with surgery and radiation
      • mortality up to 50% with high-grade disease 
Classification
  • Classification of STS is based on histology, with over 50 types recognized
    • all STS have the same presentation, imaging, differential diagnosis, and treatment
    • histologic findings and molecular signatures are used to distinguish individual types  
    • commonly tested soft tissue sarcomas include
      •  undifferentiated pleomorphic sarcoma (UPS; previously malignant fibrous histiocytoma)
      •  malignant peripheral nerve sheath tumor (MPNST)
      •  synovial sarcoma
      •  liposarcoma
      •  rhabdomyosarcoma
      •  fibrosarcoma
      •  leiomyosarcoma
      •  epithelioid sarcoma
      •  angiosarcoma
      •  dermatofibrosarcoma protuberans
      • clear cell sarcoma
      • alveolar soft part sarcoma (ASPS)
Presentation
  • Symptoms
    • slow growing, painless mass 
      • incidental trauma often draws attention to mass
  • Physical exam
    • inspection
      • mass may be palpable
      • lack of ecchymosis suggests an encapsulated mass 
        • could contradict diagnosis of hematoma, which typically presents with ecchymosis after trauma
    • palpable soft tissue lesion
      • differentiation of whether a mass is above or below fascia has prognostic importance 
      • size > 5 cm in cross-section is a poor prognostic factor
    • can be confused with more common pathology 
      • lipoma
      • hematoma
Imaging
  • Radiographs
    • indications
      • obtain plain radiographs in at least two planes for initial workup 
  • CT chest
    • indications
      • obtain to assess for metastatic disease
  • MRI
    • indications
      • mandatory to evaluate soft tissue lesions in the extremities and determine treatment algorithm
    • findings
      • T1: low signal intensity (isointense with muscle)
      • T2: high signal intensity
      • IV gadolinium: peripheral enhancing zone and non-enhancing necrotic center 
    • can diagnostic for the following benign lesions
      • lipoma topic 
      • neurilemoma (schwannoma) topic 
      • intramuscular myxoma topic
      • if MRI is diagnostic and the mass is benign and symptomatic, then it can be removed without a biopsy
    • indeterminate MRI
      • if MRI is indeterminate or suggestive of sarcoma, then a core needle or open biopsy must be obtained before further treatment is initiated 
      • soft tissue sarcomas can look similar to hematomas, so be cautious of a "hematoma" which occurs without trauma
Studies
  • Histology  
    • determined by type of sarcoma
      • undifferentiated pleomorphic sarcoma 
      • malignant peripheral nerve sheath tumor 
      • synovial sarcoma  
      • liposarcoma 
      • rhabdomyosarcoma 
      • fibrosarcoma 
      • leiomyosarcoma 
      • epithelioid sarcoma 
      • angiosarcoma 
      • dermatofibrosarcoma protuberans 
Treatment
  • Operative
    • radiation therapy & wide surgical resection     
      •  indications
        • standard of care in most cases
        • treatment must be based on a tissue diagnosis unless images are diagnostic (i.e. lipoma) 
      • radiation therapy
        • an important adjunct to surgery decreasing local recurrence
        • timing of radiation does not impact overall survival 
        • 50-60 Gy is the standard dose for soft-tissue sarcomas 
        • radiotherapy may be given pre- or postoperatively
          • pre-operative radiotherapy is associated with a > 30% risk for wound complications
          • post-operative radiotherapy is associated with greater radiation-induced morbidity and an increased risk of radiation-induced sarcoma
        • Early effects: desquamation, delayed wound healing, infection
        • Late effects: fibrosis, post-radiation fracture, possible secondary sarcoma
          • prophylactic plate or IMN fixation should be considered
      • chemotherapy
        • controversial for soft tissue sarcomas
        • considered standard of care for rhabdomyosarcoma and Ewing sarcoma
      • surgical resection
        • must confirm border free of disease with histology
    • surgical resection of lung metastases (wedge resection or lobectomy)
      • indications
        • first-line for pulmonary metastases if the preop evaluation shows that complete resection is possible
      • results
        • long-term survival is possible for select patients
Complications
  • Recurrence
    • local recurrence <10% with radiation and surgery
    • following resection, the most common location for recurrence of a low-grade STS is locally 
  • Unplanned excision 
    • CT chest, abdomen, pelvis to exclude metastasis
    • MRI of the limb to determine the degree of contamination, post-operative changes, and to assess margins
    • revision surgery
      • limb salvage + radiation therapy
      • amputation
    • unplanned excision is associated with higher plastic reconstruction of the affected region 
 

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Technique Guides (1)
Questions (27)
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(OBQ13.4) A 64-year-old man presents with forearm swelling. A gadolinium-enhanced MRI of his forearm is shown in Figure A and a CT scan of his chest is shown in Figure B. The lesion is resected and its gross and cellular histological appearance is shown in Figure C and D respectively. Fluorescence-in-situ-hybridization is negative for t(X:18) and t(12:16). Immunohistochemistry is negative for desmin, myogenin and CD34. What is the most likely pathologic diagnosis? Review Topic

QID: 4639
FIGURES:
1

Alveolar rhabdomyosarcoma

11%

(278/2582)

2

Myxoid liposarcoma

8%

(219/2582)

3

Dermatofibrosarcoma protuberans

10%

(249/2582)

4

Synovial sarcoma

8%

(194/2582)

5

High-grade pleomorphic undifferentiated sarcoma

63%

(1622/2582)

L 4

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(OBQ12.57) A 58-year-old man presents to your clinic with a 4-cm deep mass in his left thigh. It has been slowly expanding over the last 6 months. Radiographs show no evidence of bony involvement or soft tissue calcifications within the lesion. Which of the following is most appropriate at this time? Review Topic

QID: 4417
1

Repeat clinical examination and radiographs in 6 months

1%

(47/3701)

2

Contrast-enhanced MRI scan

88%

(3263/3701)

3

Fine needle aspiration

2%

(83/3701)

4

Core biopsy

5%

(169/3701)

5

Excisional biopsy

3%

(120/3701)

L 1

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(OBQ11.234) A 56-year-old male undergoes resection of a mass that was suspected to be a simple lipoma. The mass was contained within his sartorius muscle and shown in Figure A. The final pathology came back as a high grade soft tissue sarcoma. The treating surgeon operated completely within the sartorius compartment and did not violate any other compartments, however the final pathology showed positive margins. Staging studies show isolated disease in his right thigh. What is the most appropriate treatment for this patient? Review Topic

QID: 3657
FIGURES:
1

Amputation

1%

(41/2919)

2

Systemic chemotherapy

1%

(33/2919)

3

Radiation therapy

1%

(28/2919)

4

Wide excision of the tumor bed

22%

(646/2919)

5

Wide excision of the tumor bed followed by radiation therapy

74%

(2161/2919)

L 2

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(OBQ09.69) A 24-year-old male presents to your office with ecchymosis and a mass in the posterolateral aspect of his thigh. He states he noticed the mass approximately 6-months ago and that it has slowly been growing. He denies constitutional symptoms, is otherwise healthy, and denies any associated trauma. MRI report suggests the mass may be an organizing hematoma. Core needle biopsy in the office yields only blood. What is the next appropriate treatment option? Review Topic

QID: 2882
1

Conservative treatment - rest, ice, compression, elevation

9%

(168/1794)

2

Repeat core needle biopsy

6%

(100/1794)

3

Consult interventional radiography to place a drain under image guidance

3%

(55/1794)

4

Irrigation and debridement with initiation of postoperative antibiotics

2%

(39/1794)

5

Open surgical biopsy

79%

(1426/1794)

L 2

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(OBQ06.248) Which treatment factor has been shown to be most important for five-year disease-free survival in patients with subcutaneous sarcomas? Review Topic

QID: 259
1

Dose of chemotherapy

1%

(5/415)

2

Addition of adjuvant radiation

18%

(75/415)

3

Size of operative margin

78%

(325/415)

4

Length of chemotherapy course

1%

(5/415)

5

Addition of radiofrequency ablation

1%

(3/415)

L 2

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(OBQ06.225) A surgeon resects a small, superficial, mobile lesion from the thigh. Pathological review of the specimen suggests it is a low-grade soft tissue sarcoma with positive surgical margins. After staging the patient, no other sites of disease are identified. What is the next most appropriate treatment for this patient? Review Topic

QID: 236
1

Observation

3%

(41/1424)

2

Systemic chemotherapy

3%

(41/1424)

3

Radiotherapy

7%

(106/1424)

4

Tumor bed re-excision

86%

(1226/1424)

5

Amputation

0%

(6/1424)

L 2

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(OBQ05.231) Sixty Gy is a typical radiation dose for which of the following indications? Review Topic

QID: 1117
1

Prevention of post-operative heterotopic ossification

30%

(193/634)

2

Neoadjuvant radiation therapy for a high-grade chondrosarcoma

6%

(38/634)

3

Adjuvant radiation therapy for a high-grade osteosarcoma

10%

(62/634)

4

Adjuvant radiation therapy for a soft-tissue sarcoma

42%

(266/634)

5

Palliative therapy for a painful adenocarcinoma metastasis in the thoracic spine

11%

(67/634)

L 4

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(OBQ04.184) What is the correct treatment for an incompletely excised high grade superficial sarcoma on the volar aspect of the forearm? Review Topic

QID: 1289
1

Chemotherapy

1%

(11/1523)

2

Radiation therapy

4%

(64/1523)

3

Marginal resection of the tumor bed to spare the neurovascular bundles

4%

(65/1523)

4

Wide resection of the tumor bed and coverage as necessary

90%

(1372/1523)

5

Palliative care

0%

(4/1523)

L 1

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(OBQ04.260) A 39-year-old male is diagnosed with myxoid liposarcoma of the thigh. Radiation therapy is being considered in adjunct to surgical excision. Which of the following is true regarding radiation therapy in soft tissue sarcoma? Review Topic

QID: 1365
1

Compared to post-operative radiation, pre-operative radiation is associated with a reduced rate of wound dehiscence

7%

(100/1388)

2

Radiation therapy reduces the risk of local recurrence

73%

(1017/1388)

3

Radiation therapy improves overall survival

8%

(111/1388)

4

Compared to post-operative radiation, pre-operative radiation is associated with increased rates of radiation induced morbidity such as post-radiation fibrosis

10%

(142/1388)

5

Radiation therapy decreases the chances of successful limb-salvage

1%

(11/1388)

L 2

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(OBQ04.106) A 52-year-old male presents with 6 months of swelling and pain in his leg. He states the lesion has not changed in size for several months and doesn't bother him. He is otherwise healthy and has no other complaints. Representative photograph and MRI are shown in Figures A through C. What is the best initial step in his management? Review Topic

QID: 1211
FIGURES:
1

Follow-up in 6 months with repeat radiographs

1%

(7/837)

2

Biopsy

91%

(758/837)

3

Marginal excision

3%

(28/837)

4

Radiation therapy

0%

(2/837)

5

Neoadjuvant chemotherapy and wide excision

4%

(37/837)

L 1

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